Ultrasonic washing machine and transducer therefor



Jan; 31, 1967 G. G. BROWN 3,301,535

ULTRASONIC WASHINGMACHINE AND TRANSDUCER THEREFOR Filed Jan. 4, 1966 I'9 INVENTOR.

GILBERT G. BROWN I23 I20 I23 United States Patent 3,301,535 ULTRASONICWASHING MACHINE AND TRANSDUCER THEREFOR Gilbert G. Brown, Erie, Pa.,assignor to American Sterilizer Company, Erie, Pa., a corporation ofPennsylvania Filed Jan. 4, 1966, Ser. No. 518,676 8 Claims. (Cl. 25999)This invention relates to an improved ultrasonic transducer and a methodfor mounting said transducer in such a manner that it is mechanicallyand acoustically decoupled from other transducers and/or the device towhich the transducers are mounted. Although this invention relates toultrasonic cleaning devices the transducer and its resilient mountingmay be advantageously used wherever a transducer or a mosaic oftransducers are used to perform any of the well known processes whichcan be performed by ultrasonic energy. For example, agglomeration offine particles, dispersion, homogenization, wetting of cloths in dyeing,soldering and many other well known functions.

It is well known by those skilled in the art of designing ultrasonicdevices that the coupling between tranducers as well as the couplingbetween transducers and the device to which they are attached producessuch undesirable effects as in and out of phase cancellations andfortifications of the ultrasonic energy. This condition produces hotspots when the phase relationship is additive and dead spots when therelation is out of phase by some angle. For example, when the phaserelationship is 180 there can be complete cancellation.

When transducers are attached firmly to, for example, sonic cleanertanks, the sonic energy is bled into this metal and serves no usefulpurpose. However, it does usurp energy which could have been gainfullyemployed to produce cavitation, for example, in a sonic cleaning bath orother purpose for which the device was originally designed.

Although drawings used to describe this invention relate tomagnetostrictive transducers such as are constructed of electronic gradeA nickel, nickel with cobalt additives, or other magnetostrictivemetals, it readily becomes apparent to those skilled in the art thatthis invention may be used just as advantageously with electrostrictivetransducers such as are made of barium titanate, lead zirconate titanateand other materials exhibiting the piezo-electric effect.

Ultrasonic cleaning devices are Well known in the art. The theory ofultrasonic cleaning is discussed in The Journal of Hospital Research,volume 2, number 2, July 1964, published by the Research and EducationalDivisions of the American Sterilizer Company, Erie, Pennsylvania, in anarticle by Gilbert G. Brown, et a1.

Transducers are used to generate cavitation in liquids for ultrasonic(sonic) cleaning.

The word ultrasonic and sonic are used synonymously in this applicationsince'the desirable elfects of cleaning, agglomeration, homogenizationand other functions are produced at frequencies as low as or lower thansixty (60) cycles per second and at frequencies up even into mountingshave failed because the methods utilized f ce would, in some instances,decouple the transducers but would not provide a liquid proof seal.

The present invention utilizes a transducer which may be made, forexample, of a stainless steel disk fixed to a laminated core made ofmagnetostrictive material and having an electrical coil wrapped aroundone or both legs of the core. The laminated core is passed through ahole in a web attached to a dual elastometric O-ring and a hole in thebottom of the cleaning tank. The transducer is clamped to the tankthrough the O-ring construction and a water tight seal is provided. 7

When the tank and transducers are assembled, the transducers areacoustically decoupled from each other and from the tank bottom. Thetransducers are thus permitted to work freely without interference,either from each other or from the tank bottom. The efliciency of thetransducer disclosed herein is very high, noise factor is low, and thereis no bleeding of sonic energy into the tank walls. Furthermore, theresults obtainable in ultrasonic cleaning are substantially improvedover the results obtainable with previously known transducers andtransducer mountings as will appear more fully hereinafter.

It is accordingly an object of the invention to provide an improvedtransducer.

Another object of the invention is to provide an improved combinationtransducer and cleaning tank.

Still another object of the invention is to provide an improvedcombination tank and transducer wherein the invention consists of thecombination and arrangement of parts hereinafter more fully described,illustrated in the accompanying drawing and more particularly pointedout in the appended claims, it being understood that changes may be madein the form, size, proportions, and minor details of constructionwithout departing from the spirit or sacrificing any of the advantagesof the invention.

In the drawing:

FIG. 1 is a view partly broken away showing a tank and a plurality oftransducers supported in the tank according to the invention;

FIG. 2 is an enlarged isometric view of one of the transducers shown inFIG. 1;

FIG. 3 is a cross sectional view taken on line.3 of FIG. 2;

FIG. 4 is a cross sectional view partly broken away of the resilientdual O-ring used in supporting the transducer shown separate and apartfrom the other elements; and

FIG. 5 is a view of another embodiment of the invention.

Now with more particular reference to. the drawing, a tank 15 is shownby way of illustration which may be considered to be a schematic view ofthe tank of an ultrasonic washing machine. The tank has a bottom 16 withtransducers 10 mounted on the bottom of the tank. The tank may besquare, rectangular, or any other suitable shape and configuration.

The bottom of the tank has holes therein which are slightly larger thanthe diameter of the part of the resilient washer referred to sometimesherein as a dual O-ring 12 at the bottom of a groove 27. Each resilientwasher 12 has an outer peripheral groove defined by webs 26 whichconnect the O-rings to the body of the washer.

The groove receives the material of the tank bottom that defines themargins of the holes therein. The transducers are energized by a highfrequency electronic generator or oscillator 22 which may be connectedto a suitable frequency voltage source through a cable 28 indicated. Theoscillator may be of any suitable capacity and construction adapted tooscillate at a desired frequency of, for example, 20,600 cycles persecond or 38,000 cycles per second.

The transducers are each made up of a plate-like disk 11 which may bemade of non-magnetic stainless steel, for example, and may be, forexample, three and one-half inches in diameter and one-eighth inchthick. Obviously, the disks could be made in other diameters and otherthicknesses and of other suitable materials, depending upon theparticular application and the resonate qualities of the system desiredas determined by the particular designer or person skilled in the art.

The disk 11 is shown by way of example fixed to the U-shaped core 19.The core 19 is made of laminations of a magnetostrictive material suchas, for example, pure electronic grade A nickel or any othermagnetostrictive material, an alloy of nickel. The laminations may be,for example, .010 inch thick, depending upon the frequency of operation.The legs of the U may be one-half inch wide and three inches long, andthe legs of the U may be spaced three-eighths inch part. The legs mayhave the projections 23 on their lower ends, which projections willretain the permanent magnet 20 in position.

As an alternate construction, the core 19 could be made of two separatestacks of rectangular laminations having a permanent magnet such as themagnet 20 at the lower end and having a piece of ferrite supportedbetween them at the upper end to complete the magnetic circuit and beingintegrally attached, as shown in FIG. 3.

A retainer band 21 of non-magnetic material is supported around thelower ends of the laminations to prevent them from being spreadoutwardly.

The permanent magnet 20 may be a ceramic magnet of the high strengthvariety which are familiar to those skilled in the art. It may be, forexample, one and threeeighth inch 'Wide by one and three-eighth inchlong and three-eighth inch thick. It will be magnetized with its northand south poles dis-posed on opposite sides; that is, it will bemagnetized across its lesser dimension.

Instead of a permanent magnet, suitable D.C. winding could be providedin accordance with common practice in transducers of this type.

The disk 11 will be fixed to the end of the U-shaped member by means ofepoxy cement, silver brazing, or other suitable methods.

The coil 18 will be designed of proper wire size and number of turns togive the proper ampere turns and electrical impedance match desired in amanner familiar to those skilled in the art. The coils will be connectedto an oscillator or power supply 22 in suitable fashion and will besupported over the legs of the laminations 19 with a coil form 17 orsuitable insulating material between the laminations and the coilwindings.

The washer 13 may be a plain washer made of relatively rigid materialsupported below the resilient washer 12 and clamped to the disk 11 bymeans of the studs 29 which will be welded or otherwise aflixed to theunderside of the disk 11. The studs 29 will extend through suitablespaced holes in the washer 13 and will be clamped thereto by means ofnuts 14.

The resilient washer 12 has the groove 27 previously mentioned and hasO-rings 25 attached to the resilient washer itself by means of the webs26. The webs 2 6 define the sides of groove 27. Thus, when the resilientwasher receives the margin of a hole in the bottom 16, it forms a liquidtight seal. The washer 13 and bottom 16 are held in the space betweenthe O-rin-gs 25, the rings are compressed between the disk 11 and thewasher 13, and leakage from the tank through the holes in its bottom isprevented.

Tests utilizing the transducers disclosed herein indicate considerablyimproved distribution of the ultrasonic vibrations in the liquid as wellas improved results in the cleaning action of the machine. Furthermore,problems of leakage from the tank are virtually eliminated.

In the embodiment of the invention shown in FIG; 5, a transducer core isshown having legs 119 made up of laminations and fixed to a disk 11 bybrazing or the like. A magnet 120 is supported above projections 123 asin FIG. 3. A piece of ferrite is disposed between the legs 119, andclose the magnetic field. When provided with coils and suitablyinstalled, the device of FIG. 5 functions like the device shown in FIG.3.

The foregoing specification sets forth the invention in its preferredpractical forms but the structure shown is capable of modificationwithin a range of equivalents without departing from the invention whichis to be understood is broadly novel as is commensurate with theappended claims.

The embodiments of the invention in which an exclusive property orprivilege is claimed as defined as follows:

1. In combination, a transducer adapted to be installed in a liquid tankand a sealing washer comprising,

a relatively rigid plate-like member,

actuating member fixed to one side of said plate-like member adjacentthe center thereof,

said actuating member being adapted to extend through an opening in thebottom of said tank,

a resilient washer having an opening in the center thereof,

said actuating member extending through said opening in said washer,

said washer having a groove in the outer periphery thereof,

said groove being adapted to receive the peripheral edge defining saidopening in said tank,

and sealing means to seal said washer to said disk and to said tankwhereby leakage between said tank bottom and said transducer iseliminated.

2. The combination recited in claim 1 wherein said sealing meanscomprises two rings O-sha-ped in cross section,

said rings being integrally attached to the outer periphery of saidwasher,

said rings being dispose-d on opposite sides of said groove from eachother.

3. The transducer recited in claim 1 wherein said transducer comprisessaid plate-like member fixed to a magnetostrictive member.

4. The transducer recited in claim 3 wherein a relatively rigid washeris disposed in engagement with said resilient washer on the side thereofremote from said disk,

and means attached to said disk and extending through said resilientwasher whereby said rigid washer is clamped to said disk with said ringssqueezed there between.

5. The transducer recited in claim 1 wherein said actuating meanscomprises an elongated member made of magnetostrictive material,

and a coil wrapped around a part of said elongated member,

said coil being adapted to be connected to a source of energy ofultrasonic frequency.

6. In combination, a tank and a plurality of transducers,

said tank having spaced openings in the bottom thereof,

each said transducer comprising,

a relatively rigid plate-like member,

actuating member fixed to one side of said plate-like member adjacentthe center thereof,

said actuating member being adapted to extend through an opening in thebottom of said tank,

a resilient washer having an opening in the center thereof,

said actuating member extending through said opening in said washer,

said washers each having a groove in the outer periphery thereof,

each said groove receiving the peripheral edge defining one of saidopenings in said tank,

and sealing means to seal said washers to said disks and to said tankwhereby leakage between said tank bottom and said transducer iseliminated.

7. The combination recited in claim 6 wherein means is attached to saiddisk and extends through said washer clamping said washer to said tank.

8. The combination recited in claim 6 wherein said means to clamp saidtransducers to said tank comprises threaded members fixed to said disksand ex.- tending through said r-igid washers.

References Cited by the Examiner UNITED STATES PATENTS 2,616,820 11/1952Bourgeaux 1341-84 2,896,649 7/1959 Faidley 134184 3,113,761 12/1963Platzman 134-484 3,198,489 8/1965 Finch 259-1 WALTER A. SCHEEL, PrimaryExaminer.

15 R. W. JENKINS, Assistant Examiner.

1. IN COMBINATION, A TRANSDUCER ADAPTED TO BE INSTALLED IN A LIQUID TANKAND A SEALING WASHER COMPRISING, A RELATIVELY RIGID PLATE-LIKE MEMBER,ACTUATING MEMBER FIXED TO ONE SIDE OF SAID PLATE-LIKE MEMBER ADJACENTTHE CENTER THEREOF, SAID ACTUATING MEMBER BEING ADAPTED TO EXTENDSTHROUGH AN OPENING IN THE BOTTOM OF SAID TANK, A RESILIENT WASHER HAVINGAN OPENING IN THE CENTER THEREOF, SAID ACTUATING MEMBER EXTENDINGTHROUGH SAID OPENING IN SAID WASHER, SAID WASHER HAVING A GROOVE IN THEOUTER PERIPHERY THEREOF, SAID GROOVE BEING ADAPTED TO RECEIVE THEPERIPHERAL EDGE DEFINING SAID OPENING IN SAID TANK, AND SEALING MEANS TOSEAL SAID WASHER TO SAID DISK AND TO SAID TANK WHEREBY LEAKAGE BETWEENSAID TANK BOTTOM AND SAID TRANSDUCER IS ELIMINATED.